Field
Various communication systems may benefit from improvements in communication flow. For example, a network may benefit from packet flow optimization.
Description of the Related Art
Network function virtualization is discussed in, for example, “Network Functions Virtualization (NFV); Architectural framework”, a draft ETSI Group Specification GS NFV 002 v1.1.1, “Network Functions Virtualization (NFV); Management and Orchestration”, a draft ETSI Group Specification GS NFV-MAN 001 v0.0.11 and “Network Functions Virtualization; Use Cases”, a draft ETSI Group Specification GS NFV 009 v0.1.6, each of which is hereby incorporated herein by reference in its respective entirety.
In this environment, the virtualized network entities can be managed by a network function virtualization orchestrator (NFVO). The NFVO can dynamically and automatically distribute and maintain virtualized network functions in the infrastructure. For example, the NFVO can set up virtual machines (VMs) to run on given physical machines (PMs) and can set up virtual network functions/entities to run on the VMs, as well as define, allocate, and scale resources to the virtual entities and machines. The NVFO may also have an interface to legacy O&M functions to utilize existing O&M functionalities.
One example of network function virtualization is virtualization of the 3GPP mobile network environment. One distinct area within the 3GPP environment is the evolved packet core (EPC), which contains both pure control plane entities, such as the mobility management entity (MME), and entities with both a control plane (CP) and user plane (UP), such as the gateway entities, including serving gateway (S-GW), packet data network (PDN) gateway (P-GW), and in certain conditions serving general packet radio system (GPRS) support node (SGSN).
Concerning the gateway entities with both the CP and UP, two different approaches have been considered. FIG. 1 illustrates a first approach, in which an application level control plane is virtualized while a user plane is not virtualized. Thus, in FIG. 1, the application level control plane (CP) is virtualized and consequently resides and runs on a virtual machine (VM). By contrast, the user plane (UP) is not virtualized, and thus resides and runs on a dedicated hardware platform. This can be applied to both an S-GW and a P-GW in a 3GPP EPC environment, as shown. The access network protocol in this example is GPRS tunneling protocol (GTP). The user plane part, GTP-U, is terminated on P-GW user plane.
FIG. 2 illustrates a second approach, in which both the application level control plane and user plane are virtualized. Thus, both the application level CP and UP reside and run on a virtual machine. FIG. 2 describes this approach and principle, as applied to both an S-GW and a P-GW in a 3GPP EPC environment. The access network protocol in this example is GTP, as in FIG. 1. The user plane part, GTP-U, is routed via the virtual machines (VMs) and terminated on P-GW user plane on the virtual machine VM-2.
In the first approach, as illustrated in FIG. 1, the application specific user plane functionalities, such as traffic detection, usage reporting, policy and charging enforcement, event reporting, and the like, are still running on dedicated hardware. This need for the dedicated hardware to run application specific user plane functionalities can effectively reduce the benefits of virtualization. For example, there is no flexibility to adjust hardware and software resources according to the needs created by the traffic situation.
Furthermore, the first approach may require a new CP interface between the virtualized application control plane and the non-virtualized application user plane. This interface may be overloaded with application specific features, and may require control information between CP and UP function.
In the second approach, all user plane traffic goes from the internet protocol (IP) router level, which is typically from dedicated hardware, via the input/output (I/O) circuitry of the VM environment and platform, to the virtualized application user plane on the VM, and back from the VM to the IP router level. In case of high rate or volume traffic flows this is a potential bottle neck in the traffic channel, limiting the number of simultaneous high rate or volume connections and/or the data rates in general. This may also require a highly optimized I/O solution on the VM environment. Delay may be increased by the extra legs of routing the traffic via the application user plane on the VM. Furthermore, since UP function and CP function are always mapped 1 to 1, there is lack of flexibility in choice of UP function and possible bottleneck due to such a mapping.